This invention relates to abrasive flow machining and is more particularly directed to a new and improved method for flowing an abrasive flow composition and the tooling useful in practicing same. The present invention is particularly useful in radiusing small holes as well as in polishing the surfaces defining said holes e.g. in workpieces such as steel, aluminum, titanium and nickel alloy, et cetera. Abrasive flow machines are at this time well known in the art and are disclosed for example in U.S. Pat. Nos. 3,728,821; 3,769,751; 3,039,234; 2,346,228, among others.
Suitable abrasive flow compositions for use in this invention is disclosed in U.S. Pat. No. 2,346,228 or are sold by Dynetics Corp. of Woburn, Mass. under the trademark DYNAFLOW. As may be observed from the aforementioned U.S. Pat. Nos. 3,728,821 (FIG. 2) and 3,769,751 (FIG. 2) the flow of the abrasive composition is directly through holes in a workpiece held by a tool in order to remove material therefrom.
While such a machining scheme as shown in the aforementioned patents are quite useful where large diameter holes (e.g. greater than 20 mils diameter) are to be worked, it has been extremely difficult and in some cases well nigh impossible to force the flowable abrasive composition through small diameter holes such as to perform work thereon in a useful manner for commercial purposes. Using the prior art technique as shown in the aforementioned patents, abrasive flow through small holes in a workpiece when machining same essentially stops just as if the holes were in a sense absent or plugged up.
Thus a new and improved method and tooling therefore was needed to permit abrasive flow machining of small holes in workpieces i.e. holes less than 20 mils in width and as small as 1 to 5 mils in width. Applicant has unexpectedly discovered as will be disclosed herein a method and tooling for practicing same which permits machining of small holes.
As used herein the term abrasive flow machining of a hole is intended to mean the removal of material of the workpiece defining the hole so as to radius the entrance and exit of the hole as well as to polish same. The present invention is particularly applicable for abrasive flow machining of holes of extrusion dies or other perforated components.
The present discovery with certain modifications as will be disclosed herein also unexpectedly provides a solution to another problem which has plagued industry i.e. radiusing a large hole without substantial removal of the material between the exit and entrance of the hole such as holes in a jet engine rotor.